In the railroad industry, it has been generally known, prior to the present invention, to use standard couplers that have been given prior approval for use by the Association of American Railroads (AAR). These standard couplers are used to connect adjacent ends of a pair of railway cars together. For example, in this application, such standard couplers were generally designed to facilitate both the connecting and disconnecting of individual railway cars forming a train consist. Such couplers enable these car to be readily and easily combined to make up the train consist or to be individually separated as necessary for loading and unloading purposes.
However, in more recent times, the railroad industry has discovered that the interconnecting of a number of railway cars together to form a substantially semipermanent unit has a number of important and distinct advantages. By way of example, these advantages are achieved when such railway cars are particularly designed for use in "piggy back" service and have been joined together in such semipermanent manner. Railway cars which have been joined in this semipermanent fashion are commonly referred to, in the railroad industry, as either a "five pack" or a "ten pack" unit. These particular units do not require the use of the standard AAR approved coupler discussed above, except between units. In other words, on the ends of such "five pack" or "ten pack" units. The principle reason such standard couplers ar not required in this application is because these units are only broken on a periodic basis. As a general rule, this occurs only when maintenance or replacement of an individual component must be carried out. Obviously, this enables considerable cost savings to be achieved with this arrangement. These cost savings are derived from lower weight, fewer railway trucks, reduced maintenance, and lower equipment cost. Such lower weight discussed above, as well as the reduced equipment cost which can be obtained, is achieved in part by the elimination of the need for draft gear assemblies in addition to the number of trucks required. It being understood that such draft gear assemblies are still required at each end of such "five pack" or "ten pack" units.
With the extended us of the semipermanent articulated coupler arrangements, and with the higher loads being carried by modern railway trucks, it is of the utmost importance that a close buttoned relationship be maintained between the draft components of the articulated coupling arrangement during in-track service. Such close buttoned relationship being required so that a reduction of the effects of the impact forces, which are normally encountered under buff conditions of train operations, can be achieved.
Taught in U.S. Pat. No. 4,258,628 is one of the prior art type of articulated coupling arrangements used for the purpose of connecting adjacent ends of a pair of railway cars together in a substantially semipermanent manner. This particular articulated coupling arrangement includes a male connection member secured at one end thereof to one end of a first railway car body member and a female connection member secured at one end thereof to an adjacent end of a second railway car body member. The female connection member, in this arrangement, is rotatably engaged in a center plate bowl portion of a bolster disposed on a railway car truck in a manner that is generally well recognized in the railway art. The outer end of the male connection member, in this prior art arrangement, is disposed for movement within a cavity that is formed in the outer end of such female connection member.
As illustrated in the drawings of this reference, both the male connection member and the female connection member are joined in a substantially semipermanent manner by a pin member. Such pin member is positioned in a vertical direction and is disposed in aligned apertures formed in each of the male connection member and the female connection member. It can =seen that the aperture formed in such male connection member for receiving the pin member therein must be somewhat larger than the pin member itself. Such larger aperture in the male connection member is required to achieve certain necessary movements of the articulated coupling arrangement. The rear surface portion of the aperture formed in the male connection member which receives such pin member therein has a horizontally disposed concave configuration and a vertically disposed convex configuration. This particular configuration enable both the male connection member and the female connection member to move in each of a horizontal direction and a vertical direction in relationship to one another, while at the same time, providing a relatively substantial area of surface contact between the rear surface, the pin member aperture, and the pin member.
The outer end surface of the outer end of the male connection member includes a convex configuration which abuts against a complimentary concave surface formed on a front face of a follower member. In this prior art articulated coupling device, the follower member is carried within the rear portion of the cavity formed in the outer end portion of the female connection member. This prior art device has a pair of vertically disposed slot-like cavities formed on the rear face of such follower member. Each of these vertical slots has a resilient element disposed therein. Such resilient element projects outwardly from the rear face of such follower member. The associated outer surface of each such resilient element is engaged by a vertically disposed wedge element. This wedge element is provided to urge the follower member and the male connection member forward. In this manner, the rear surface portion of the aperture formed in the male connection member will be maintained substantially in contact with such pin member at all times during operation.
This contact is necessary in these prior art articulated coupling arrangements because the majority of the articulated connecting parts are formed as cast members. Consequently, in order to reduce the cost of this coupling arrangement, such cast members will receive very little, if any, finished machining to provide the necessary or desirable dimensional control. As a result of this, it is rather difficult to provide an articulated coupling device which is self-adjusting under the various wear conditions which such coupling device will normally be subjected to during in-track service.
Other prior art articulated coupling devices are taught in U.S. Pat. No. 3,716,146 and Canadian Pat. No. 1,231,078.